Cotyledon explants of Panax ginseng were cultured on modified Murashige and Skoog medium with various concentrations of NH4Cl and KNO3. Morphogenesis such as somatic embryo, embryogenic callus, or adventitious root formation from cotyledon explants differently occurred according to the concentrations of NH4+ and NO3-. Somatic embryos were actively formed in a moderate concentration of NH4+(20 mM) in combination of NO3-, but in a high concentration of NH4+ (60 mM), only embryogenic calli were formed. In little or no NH4+, adventitious roots were formed at a high rate. the influence of NO3- on those morphogenesis was slight but combination of NO3- with NH4+ was indispensable since the cotyledon explants were necrotized on medium containing only NH4+ as a nitrogen source. Histological observation revealed that somatic embryo and embryogenic callus formation occurred from the same origin (cotyledon epidermis), whereas, adventitious roots were originated from the cells near vascular strands.